1. Field of the Invention
The present invention relates to the field of large capacity low voltage switching apparatus, more particularly, relates to a manual operation device for large capacity low voltage switching apparatus.
2. The Related Art
In low voltage electrical appliance field, large capacity switching apparatuses, such as automatic transfer switches with a rated current over 4000 A, circuit breaker products with a rated current over 4000 A, require a large manual operating force to achieve energy storage operation and close-open operation of the switching apparatus due to their large capacity. According to the IEC standard, a required manual operating force shall be controlled under 250N. A large required manual operating force may cause difficulties in manual operations, and will be a potential risk in safety.
In existing switching apparatuses, the rotation center of a manual operation handle of an operation mechanism and the rotation center of a shaft which drives an energy storage mechanism are concentric. Such a structure is compact and convenient to realize, but requires a very large manual operating force when applied in large capacity switching apparatuses, sometimes may even cause manual operation difficulties. For automatic transfer switches with a single handle and dual energy storage mechanisms, such a structure is feasible for products with a rated current under 1600 A. However, for a product with a rated current over 4000 A, the manual operating force required by this structure is too large and will significantly influence the reliability of operations. Therefore, a new operating handle with a reasonable operating force is demanded.